1. Field of Invention
The present invention relates to means for electrical measurement of hematological parameters, and more particularly to means for providing an indication of mean corpuscular volume of blood cells in a diluted sample.
2. Description of the Prior Art
Mean corpuscular volume refers to the average size of red blood cells in a blood sample. The context comtemplated for the present invention is a blood cell counter using a conductivity sensor, having an aperture through which a diluted blood sample is passed, and having electrodes on either side of the aperture. Sensor pulses are produced indicative of the number of blood cells in the sample passing through the aperture. An example of such an apparatus is disclosed in U.S. Pat. No. 3,921,066, issued to Angel, et al. on Nov. 18, 1975, now owned by the assignee herein, the disclosure of which is incorporated herein by reference. The context further contemplated is an apparatus in which measurement of the hematocrit of the blood sample is made. Hematocrit is the percentage of red blood cell volume out of the entire volume of a blood sample. Examples of hematocrit measuring apparatus are found in U.S. Pat. No. 3,828,260, issued to Underwood on Aug. 6, 1974, and now owned by the assignee herein, and co-pending commonly assigned patent application Ser. No. 725,268, filed Sept. 21, 1976, also assigned to the assignee herein.
Prior circuits have been provided for deriving outputs indicative of mean corpuscular volume including discriminating circuitry for segregating sensor output pulses within ranges of magnitude and providing an averaging calculation. Such arrangements are not only rather cumbersome, but may be subject to error as being based on non-coincidence corrected red blood cell counts.